Pre-hemming tool for robotic hemming

ABSTRACT

A pre-hemming tool for robotic hemming includes a face and a plurality of sides extending from the face. The perimeter of the face defines an edge. At least one facet is disposed on a side thereof for effecting pre-hemming. The pre-hemming tool is capable of quickly and accurately pre-hemming a variety of workpiece corner configurations.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional Application No. 60/652,358 filed Feb. 11, 2005.

TECHNICAL FIELD

This invention relates to robotic roller hemming and more particularly, to pre-hemming of closure panels such as vehicle door panels, hood panels, gate panels, and decklid panels.

BACKGROUND OF THE INVENTION

It is known in the art relating to robotic roller hemming to pre-hem sheet metal fabricated parts, such as vehicle closure panels, to a pre-hem condition prior to the hemming of the closure panels. A vehicle closure panel may consist of an outer panel and an inner panel, which are hemmed together in the hemming process to make a closure panel assembly. In the hemming process, it is known to pre-hem the outer corners of a closure panel, for example by bending the corners of the outer panel towards the inner panel, prior to hemming the outer panel completely to the inner panel. Known methods for pre-hemming closure panels utilize robotic roller hemmers to hem the corners of the outer panel over the inner panel. These methods, however, require several passes with the hem roller and therefore require a significant amount of time. Further, use of a robotic roller hemmer does not always lead to a quality corner pre-hem, as a roller hemming tool does not have the shape required to accurately make a corner pre-hem. Instead, the roller hemming tool is often ineffective for corner pre-hem operations.

SUMMARY OF THE INVENTION

The present invention provides a pre-hemming tool for robotic hemming that is able to operate at faster speeds than prior devices, thereby decreasing the amount of time required to complete the pre-hem operation. Further, the present invention will assure a higher quality pre-hem, more consistent results, and lower costs.

More particularly, a pre-hemming tool in accordance with the present invention includes a face and a plurality of sides extending from the face. The perimeter of the face defines an edge. The tool further includes at least one facet disposed on a side thereof for effecting pre-hemming.

In a specific embodiment, a facet may be disposed on each side of the tool. Each facet may be a depression, and each depression may extend from the edge inwardly and have greater side penetration than face penetration. Each depression may have a generally triangular shape when viewed from the side. Each depression may include two triangularly shaped surfaces or alternatively may include a floor and a sidewall extending from the floor.

The pre-hemming tool may have four sides and may be made of a flame hardenable tool steel. Alternatively, the tool may have six sides, though any other number of sides is also within the scope of the invention.

Optionally, the pre-hemming tool may further include a support opposite the face. The support may be a plate and may either be integral with the tool or mounted to the tool.

The pre-hemming tool may be adapted for releasable connection to a robot arm and may include an automatic change out tool operatively, releasably connected to the pre-hemming tool for mounting the pre-hemming tool to a robot arm.

In an alternative embodiment, the pre-hemming tool may include guide members adjacent the sides of the tool. The guide members may be rails generally extending along the sides and may be adapted to engage receivers on a hemming die.

These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1A is an environmental perspective view of a pre-hemming tool for robotic hemming in accordance with the present invention performing a pre-hem operation via a robotic arm;

FIG. 1B is a front view of the pre-hemming tool viewed from the direction 11 in FIG. 1A;

FIG. 2 is a perspective view of the pre-hemming tool of FIG. 1A;

FIG. 3 is a perspective view of an alternative embodiment of a pre-hemming tool in accordance with the present invention illustrating a six-sided working member;

FIG. 4 is an environmental perspective view of the pre-hemming tool of FIG. 1A illustrating the pre-hemming tool in a retracted position relative to a corner of a panel;

FIG. 5 is an environmental perspective view of the pre-hemming tool of FIG. 1A illustrating the pre-hemming tool in a working position relative to a corner of a panel; and

FIG. 6 is a perspective view of another embodiment of a pre-hemming tool in accordance with the present invention illustrating guide members of the pre-hemming tool.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, numeral 10 generally indicates a multi-faceted pre-hemming tool in accordance with the present invention that is capable of pre-hemming a variety of workpiece corner configurations. The pre-hemming tool 10 is also capable of quickly pre-hemming all the corners of a workpiece, thereby decreasing cycle time and operation costs. The pre-hemming tool 10 is also capable of more accurate and consistent pre-hemming results due to the tool being specifically shaped to perform specific pre-hemming operations.

FIG. 1A generally illustrates a robotic arm 12 used for hemming a workpiece 14 supported by a hemming die 16. The workpiece 14 may be a closure panel such as a door panel, hood panel, gate panel, or decklid panel, and may include an inner panel and an outer panel. The robotic arm 12 may operate the pre-hemming tool 10 to pre-hem the corners a,b,c,d of the workpiece 14. For example, the pre-hemming tool 10 may pre-hem the workpiece 14 by bending an edge of an outer panel of the workpiece 14 located at corner a from an orientation of approximately 90 degrees relative to an inner panel to an approximately 45 degree angle relative to the inner panel. Further, the robotic arm 12 may sequentially move the pre-hemming tool 10 to the other corners b,c,d of the workpiece 14 to pre-hem those corners. As seen in FIG. 1B and as described in more detail below, the pre-hemming tool 10 generally includes features A,B,C,D that allow it to be used to pre-hem the different configurations of the respective corners a,b,c,d of the workpiece 14 (e.g., feature A pre-hems corner a, feature B pre-hems corner b, etc.).

More particularly, as shown in FIG. 2, a pre-hemming tool 10 includes a face 18 and a plurality of sides 20 extending from the face 18. The perimeter of the face defines an edge 22. The tool 10 further includes at least one facet 24 disposed on a side 20 thereof for effecting pre-hemming. Each facet 24 is a configuration designed to perform a pre-hem operation and each facet 24 thereby effects a condition or shaping outcome during pre-hem operations. In the embodiment shown in FIG. 2, the pre-hemming tool 10 has four sides 20, though it should be understood that any other number of sides is within the scope of the invention. The pre-hemming tool 10 may be made of a flame hardenable tool steel or similar material.

In a specific embodiment, a facet 24 may be disposed on each side 20 of the tool 10. Since the embodiment of FIG. 2 has four sides 20, it may then have four facets 24. It should be understood, however, that it is within the scope of the invention for facets 24 to be disposed on some but not all of the sides 20. For example, a facet 24 may be disposed on three of four sides 20 of the tool 10. Each facet 24 may be a depression, and each depression may extend from the edge 22 inwardly and have greater side 20 penetration than face 18 penetration. Each depression may have a generally triangular shape when viewed from the side. Each depression may include a floor 26 and a sidewall 28 extending from the floor 26. Each facet 24 may also be of a different size to allow the pre-hemming tool 10 to be used for a variety of pre-hem operations.

Optionally, a support 30 may be disposed opposite the face 18. The support 30 may be a plate, disc, or similar. The support 30 may be integral with the tool 10 or may be mounted to the tool.

Turning to FIG. 3, a pre-hemming tool 110 is shown having six sides 120 and one facet 124 per side 120. The pre-hemming tool 110 otherwise has features similar to the four-sided tool embodiment 10 of FIG. 2. The six-sided tool 110 may be used to pre-hem a workpiece having up to six different corner configurations while the four-sided tool 10 may be used to pre-hem a workpiece having up to four different corner configurations. Although the pre-hemming tool has been described herein by reference to a four-sided and a six-sided pre-hemming tool 10, 110 having one facet per side 20, 120, it should be understood that a pre-hemming tool according to the present invention may have more or fewer sides and likewise more or fewer facets for corner pre-hemming various configurations.

As shown in FIG. 1, the pre-hemming tool 10 may be adapted for releasable connection to the robot arm 12, such as a robotic arm of a robotic roller hemming robot. When the pre-hemming tool 10 is used by a roller hemming robot, an automatic change out tool (known in the industry as an “ATI”) may be required. The tool 10 may therefore include an automatic change out tool 32 (“ATI”) operatively, releasably connected to the pre-hemming tool 10 for mounting the pre-hemming tool to the robot arm 12. The ATI 32 allows heads that attach to the end of the robot arm 12 to be changed quickly and without the use of manual labor. In this case, for example, the ATI 32 will be capable of accepting the pre-hemming tool 10 as well as a roller hemming tool (not shown). When the robot needs to perform a pre-hemming operation, it will use the ATI 32 to release the roller hemming tool and to pick up the pre-hemming tool 10, thereby releasably mounting the pre-hemming tool 10 to the robot arm 12. When the pre-hemming tool 10 is attached to the robot arm 12, the robot arm 12 manipulates the tool 10 to effect a pre-hem operation. To perform roller hemming after pre-hemming with the pre-hemming tool 10, the robot arm 12 releases the pre-hemming tool 10 and then releasably mounts itself to the roller hemming tool.

With reference now to FIGS. 1A, 4, and 5, the robot arm 12 may use the pre-hemming tool 10 to effect a pre-hem as follows. A workpiece 14, such as a nested metal panel including an outer panel 34 and an inner panel 36 may be placed on a lower hemming die 16. The lower hemming die 16 may be, for example, mounted on a turntable mechanism (not shown). The outer panel 34 is placed first on the lower hemming die 16 such that it is seated in a holding piece such as an anvil 17 or similar. The inner panel 36 is then placed on top of the outer panel 34. The edge 38 of the outer panel 34 extends beyond the edge 40 of the inner panel 36 and defines an open hem flange.

A pre-hem operation involves, for example, bending the open hem flange 38 of the outer panel 34 from an orientation of approximately 90 degrees from the inner panel 36 towards the edge 40 of the inner panel 36 so that the open hem flange 38 of the outer panel 34 is bent approximately 45 degrees from the inner panel 36. The robot arm 12 will be programmed to position itself in the proper location relative to the lower hemming die 16 to perform the pre-hem operation. For example, as shown in FIG. 4, the robot arm 12 will be programmed to position itself at the anvil 17 of the lower hemming die 16 at a corner of the workpiece 14 where an open hem flange 38 is located. The pre-hemming tool 10 will be aligned with a corner of the workpiece 14 such that a facet 24 of the pre-hemming tool 10 is aligned with the open hem flange 38. As shown in FIG. 5, the robot arm 12 will then move the pre-hemming tool 10 forward in a straight line, causing the aligned facet 24 of the pre-hemming tool 10 to apply a force on the open hem flange 38, thereby bending the open hem flange 38 45 degrees towards the inner panel 36, completing the pre-hem operation. The robot arm 12 will then move the pre-hemming tool 10 backwards away from the hemming die 16 until the pre-hemming tool 10 is clear of the workpiece 14 and the lower hemming die 16.

The robot arm 12 may then move to another corner of the lower hemming die 16 and hence another corner of the workpiece 14 to perform another pre-hem operation. At this time, the robot arm 12 may rotate the pre-hemming tool so that another facet 24 may be aligned with a corner of the workpiece 14. In the case that pre-hemming tool is four-sided with one facet 24 per side, the robot arm 12 rotates the tool 10 90 degrees, or any multiple of 90 degrees, so that another facet 24 may be aligned with a corner of the workpiece 14. Likewise, if the pre-hemming tool is six-sided as in FIG. 3, the robot arm 12 would rotate the tool a multiple of 60 degrees to align another facet with a corner of the workpiece. Generally, the robot arm 12 will rotate the tool a multiple of 360 divided by the number of sides of the tool. After rotating the tool 10, the robot arm 12 will perform another pre-hem operation as described above. The robot arm 12 may then continue on to yet another corner of the workpiece 14 until all of the corners of the workpiece 14 are pre-hemmed. Since the embodiment shown in FIGS. 1A, 4, and 5 has four facets 24, the robot arm 12 may use the pre-hemming tool 10 to pre-hem up to four separate pre-hem conditions or shaping outcomes on the same outer panel.

Turning to FIG. 6, in an alternative embodiment, a pre-hemming tool 210 in accordance with the present invention may include guide members 242 adjacent the sides 220 of the tool 210. The guide members 242 may be rails generally extending from the edge 222 along the sides 220. For example, one guide member 242 may be disposed along the length of each side 220 of the tool 210. The guide members 242 may be adapted to engage receivers (not shown), such as a slot, track, or similar, located on a hemming die at a corner thereof. The receivers on the hemming die are positioned to ensure that the pre-hemming tool 220 is properly aligned with the corners of a workpiece each time a robot arm holding the tool 220 performs a pre-hem operation. The guide members 242 on the pre-hemming tool 210 allow for repeatable location of the pre-hemming tool 210 in addition to the already accurate positional tolerances of a robot arm. Also, in this embodiment, each facet 224 of the tool 210 may be a depression including two triangularly shaped surfaces 244.

Although the invention has been described by reference to specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims. 

1. A pre-hemming tool for robotic hemming, the tool comprising: a face and a plurality of sides extending from said face, the perimeter of said face defining an edge; and at least one facet disposed on a side thereof for effecting pre-hemming.
 2. The pre-hemming tool of claim 1, wherein a facet is disposed on each side.
 3. The pre-hemming tool of claim 1, wherein each facet is a depression.
 4. The pre-hemming tool of claim 3, wherein each depression extends from said edge inwardly and has greater side penetration than face penetration.
 5. The pre-hemming tool of claim 3, wherein said depression has a generally triangular shape when viewed from the side.
 6. The pre-hemming tool of claim 3, wherein said depression includes two triangularly shaped surfaces.
 7. The pre-hemming tool of claim 3, wherein said depression includes a floor and a sidewall extending from said floor.
 8. The pre-hemming tool of claim 1, wherein said tool has four sides.
 9. The pre-hemming tool of claim 1, wherein said tool has six sides.
 10. The pre-hemming tool of claim 1, wherein said tool is made of a flame hardenable tool steel.
 11. The pre-hemming tool of claim 1, further including a support opposite said face.
 12. The pre-hemming tool of claim 11, wherein said support is a plate.
 13. The pre-hemming tool of claim 1, wherein said tool is adapted for releasable connection to a robot arm.
 14. The pre-hemming tool of claim 13, including an automatic change out tool operatively, releasably connected to said tool for mounting said tool to a robot arm.
 15. The pre-hemming tool of claim 1, including guide members adjacent said sides of said tool.
 16. The pre-hemming tool of claim 14, wherein said guide members are rails generally extending along said sides, said guide members being adapted to engage receivers on a hemming die. 